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This month’s Observer’s Challenge, the dwarf elliptical galaxy NGC 147 in Cassiopeia, has been glimpsed with 7X35 binoculars yet can be a challenge for a 10-inch scope. Its 9.5 visual magnitude sounds promising, but the light is spread over an area 13 by 8 arc-minutes in size. The situation is similar to that of Barnard’s Galaxy (NGC 6822), briefly mentioned last September and featured as the August, 2014, Observer’s Challenge.

Save NGC 147 for the clearest, darkest night possible and be sure your eyes are adequately dark-adapted. Begin by training your scope on 4th magnitude omicron (ο) Cassiopeiae, located in the extreme southern part of the Queen and just 7° above the Andromeda Galaxy. Once you’ve centered omicron in the eyepiece field, work your way slowly westward. Just a degree from omicron, you should spot a slightly oval smudge of light. Don’t put a notch in your telescope tube yet! This is NGC 185, also a dwarf galaxy and similar in brightness and size to NCG 147. However, it’s more concentrated and has a higher surface brightness. NGC 147 is far less accommodating! Continue onward another degree and, if you’re lucky, you should spot an extremely faint and elongated glow. This is NGC 147! Now you can make your notch (or preferably make an entry in your observing logbook).

If you fail to see NGC 147, don’t give up. Conditions might prove more favorable on the next clear night. You can take solace in knowing that William Herschel surveyed this area in 1787. He spotted NGC 185 but failed to see NGC 147. His son, John, found the latter 42 years later.
NGC 147 and NGC 185 are satellites of the Andromeda Galaxy and, as such, are part of the Local Group. They are located 2.0 and 2.3 million light years away, respectively

astronomyconnect.com (image created with SkyX by Software Bisque) North is to the left

NGC 147 (top) and NGC 185 (lower) omicron Cassiopeiae is at bottom, center. North is to the left (www.astosurf.com)